Sahih Bukhari Volume 007, Book 068, Hadith Number 456.
Narrated By 'Aisha : That the Prophet entered upon her when she had her menses at Sarif before entering Mecca, and she was weeping (because she was afraid that she would not be able to perform the Hajj). The Prophet said, "What is wrong with you? Have you got your period?" She said, "Yes." He said, "This is a matter Allah has decreed for all the daughters of Adam, so perform all the ceremonies of Hajj like the others, but do not perform the Tawaf around the Ka'ba." 'Aisha added: When we were at Mina, beef was brought to me and I asked, "What is this?" They (the people) said, "Allah's Apostle has slaughtered some cows as sacrifices on behalf of his wives."